Possible mechanisms of DES action in producing delayed-appearance abnormalities of the vagina and cervix will be explored through the examination of the ontogeny of steroid hormone receptors in these tissues. A detailed examination of the quantity of estrogen and progesterone receptors (Re and Rp) apparent neonatally in the cytosol will be undertaken. The quality and quantity of hormone-receptor-nuclear interactions will also be examined. Competitive binding studies, Scatchard plot analysis of receptors, sucrose-glycerol density gradients, and nuclear exchange assays will be utilized for the identification and characterization of the cytosol and nuclear receptors. The underlying hypothesis is that DES, administered during the early differentiation and development of the female reproductive tract, alters either the quantity of Re and/or Rp or the quality of the hormone-receptor-nuclear acceptor site interactions in the cervix and vagina.